Lift fan scroll area control



Sept 15 1970 E. F. BEI-:LER 3,528,631

LIFT FAN SCROLL AREA CONTROL Filed Nov. 7, 1968 f. fr. Bee/er* ach/MM2? 79, 7253 ATTORNEY United States Patent O 3,528,631 LIFT FAN SCROLL AREA CONTROL Eugene F. Beeler, Cincinnati, Ohio, assignor, by mesne assignments, to the United States of America as represented hy the Secretary of the Army Filed Nov. 7, 1968, Ser. No. 774,150 Int. Cl. B63c 29/00 U..S. Cl. 244--23 7 Claims ABSTRACT F THE DISCLOSURE A lift fan is provided in each wing of a VTOL type of aircraft. In some designs one or more additional fans are provided, in the tail section of the fuselage, or at other points. Control apparatus is provided to vary the scroll nozzle areas at each fan. By closing or opening the rear fan scroll nozzle areas (or the front fan scroll nozzle areas), pitch control forces may be -varied to tilt the plane forward or backward. By opening the scroll nozzle areas at one fan, while closing the other, the degree of lift of one fan versus the other can be varied to aid in tilting the plane left or right. Other functions are possible.

BRIEF SUMMARY The control of the force exerted by vertical lift fans in a VTOL craft can be achieved in several ways. One relatively simple solution is to drive the fans at the same speed relative to each other but to vary their effective vertical force by controlling scroll nozzle areas adjacent to the fan blades. As the scroll nozzle areas on the rear versus front of a particular fan are varied the downwardly exhausting gas flow from these nozzles and the turbine will be increased or decreased. This results in increased or decreased lift force at the front or rear of the associated fan. Therefore, the vertical lift force by the fans is thereby varied with respect to one another, the lplane may be tilted left-right, or forward-backward. The present apparatus facilitates control of the scrolls to vary the effective vertical force exerted by the fans.

In the drawing:

FIG. 1 is a diagram of the control apparatus for the scrolls;

FIG. 2 is a diagram of linkages to operate a set of scrolls.

DETAILED DESCRIPTION Fan 1 is provided with scroll sections 3, 4 and fan 2 is provided with scroll sections 5, 6. Scroll nozzle areas in sections 3, 4, 5 and 6 are actuated by hydraulic jacks 7, 8, 9 and 10 respectively. If more than two fans are provided each may have similar scrolls, actuators and so In FIG. 2 is shown a detailed diagram of the control apparatus for scrolls `4 and 6. Power to hydraulic actuators 8 and 10 is controlled by servo-valves 11 and 13 (with similar valves 12 and 14 being provided for hydraulic actuators 7 and 9). Links 15 and 16 are connected to bell crank levers 17 and 18, and links 19 and 20 connect the bell crank levers to T lever 21. Lever 21 is connected to electric screw-jack actuator 22 by means of spring centering unit 23 and bell crank lever 24.

Bell cranks 17 and 18 are mounted on levers 25 and 26 which are connected, by linkages 27 and 28, to lever 29. Turnbuckle 30 permits adjustment 0f the linkages. Electric actuator 31 is connected to levers 29 and 32.

OPERATION Hydraulic jacks 7, 8, 9 and 10 vary the scroll nozzle' areas of the fans, thereby affecting the ow patterns of Patented Sept. 15, 1970 ICC gases and the effective thrust of the fans. The hydraulic jacks, in turn, are controlled by other apparatus, and the pilot, as follows.

ROLL STICK AND ROLL TRIM The pilot has direct control over the scrolls by stick motion imparted through linkage 101 to rock T lever 21 about pivot 102. (Linkage 103 interconnects sets of controls for two or more fan-scroll arrangements.) T lever 21, through linkages 19, 20, rocks bell cranks 17, 18 about pivots 104 and 105 and operates linkages 15, 16 to control hydraulic jacks 8, 10 and scrolls 4, 6 associated therewith.

It will be noted that the pilot is controlling scroll nozzle areas in scrolls 4 and 6, say the rear scrolls, through jacks 8 and 10, by the mechanism just described. An increase in gas ow through nozzles and downwardly from the rear scrolls yields an increase in lifting force on the rear side of the fans. This gives a variation in the effective thrust on the rear side of each fan. Similar mechanism may be connected to operate the nozzle areas of forward scrolls 3 and 5, preferably to close scrolls 3 and 5 as the rear scrolls 4 and 6 open, and to open as the rear scrolls close. However, it should be noted that the scrolls 3 and 4, at fan 1, close as scrolls 5 and 6, at fan 2, open. This permits roll control at the command of the pilot.

For hovering, automatic apparatus, not shown, feeds signals through connection 106 to electric actuator 22. Bell crank 24, pivoted at 107, and yieldable spring unit 23, impart force to T lever 21 as directed by signals through connection 106. Thus, roll trim is accomplished automatically during hovering. However, the pilot can override the automatic trim, by roll stick motion, through linkage 101 to T lever 21, by pilots force adequate to compress a spring in spring unit 23.

TEMPERATURE AND LOUVER FACTORS Exhaust gas temperature trim jog switches 108, 109, within the cockpit, command equal and symmetrical area changes to occur lwithin both front scroll arms or both aft scroll arms. For simplicity of illustration only one of the sets of apparatus is illustrated in FIG. 2, together with associated No. 2 temp. trim 109" switch. The temperature signal for change is introduced from switch 109 through connection 110 to electric screw jack actuator 31 which moves lever 29 about pivot 111. Linkages 27, 28 are thereby moved in opposite directions to move lever arms 25, 26 closer together, or farther apart, about pivots 112, 113. As arms 25, 26 are pivoted, closer together for example, the pivots 104, also come closer together allowing bell cranks 17, 18 to pivot outwardly. This lowers linkages 15, 16 and actuates servo valves 11, 13 in the same (downward) direction thereby actuating hydraulic jacks 8, 10 and nozzle areas of scrolls 4, 6 equal amounts in the same direction, that is, to open, or to close, scrolls 4, 6.

By apparatus similar to that described above scrolls 3, S are also actuated a like amount by temperature trim jog switch 108 (FIG. 1). The purpose of these trims is to adjust engine discharge temperature to (a) rated value for full power during initial propulsion installation and thereafter whenever ambient air temperature changes occur, and (b) to adjust the division of gas flow between fans and the pitch control system as may be needed to maintain pitch control effectiveness during low gross weight operation, or to optimize total system lift at high gross weight operation.

The lift fan louver 114 is connected to lever 32 to rock it about pivot 115. The lift fan louver is biased by fan gas output. The lift fan louver is also affected by flow of air thereover as the plane moves forward at greater speed. Therefore, pressure variations on the lift fan louver rock lever 32 and pivot 116 to thereby adjust the base connection of electric actuator 31 in accordance with fan air pressure, and air iiow at increased speed, against the louver associated with the fan. This permits an approximate scheduling of pitch gas recovery, or pitch gas into the fan, as an integrated function of fan speed and ight speed, as is understood to those skilled in the art.

Two lift fans have been described. These could be left and right wing fans. They would thereby tend to tilt the plane or hold it steady about its longitudinal fore-andaft axis. Or, such fans could be installed in the nose and tail sections for a higher degree of pitch control about the transverse axis. Or, three or four such fans could be used in the wings and nose-and-tail sections to yield additional control in all directions. The fans will be disposed outwardly from the center of gravity of the plane. In most installations there will be at least two fans. Generally speaking they will be mounted on or in the wings, or fuselage, or both, and will be disposed substantially equally and oppositely outwardly from the center of gravity of the plane.

I claim:

1. Aircraft scroll nozzle area control apparatus comprising a first fan and a second fan displaced outwardly from the center of gravity of the plane, a rst set of scroll nozzles having areas on one side of each fan and a second set of scroll nozzles having areas on the opposing side of each fan, first means responsive to engine operating temperature to adjust the areas for trimming the plane for maximum lift eliiciency in relation to the operating engine temperature, or ambient temperature, or both, and second means to adjust the scroll nozzle areas of the first and second fans oppositely, to lessen the lifting force of one fan while increasing the lifting force of the other fan, to control tilt of the plane.

2. Apparatus as in claim 1 wherein said irst means also comprises fan louver connections to adjust said scrolls in accordance with fan air velocity and air velocity due to forward motion of the craft.

3. Apparatus as in claim 2 wherein said second means comprises a manually operable roll trim stick apparatus and an automatically controlled electric actuator.

4. Apparatus as in claim 3 and means permitting the automatic actuator to be overruled by the roll trim stick apparatus.

5. Aircraft scroll nozzle area control apparatus comprising a rst fan and a second fan displaced outwardly from the center of gravity of the plane, a first set of scroll nozzles having areas on one side of each fan and a second set of scroll nozzles having areas on the opposing side of each fan, and means responsive to air velocity generated by forward motion of the shaft comprising fan louver connections to adjust said scroll nozzle areas in accordance with said air velocity.

6. Aircraft scroll nozzle area control apparatus cornprising a first fan and a second fan displaced outwardly on opposite sides from the center of gravity of the plane, a first set of scroll nozzles having areas on one side of each fan and a second set of scroll nozzles having areas on the opposing side of each fan, and means comprising a manually operable roll trim stick and an automatically controlled electric actuator to adjust the scroll nozzle areas of the iirst and second fans oppositely, to lessen the lifting force of one fan while increasing the lifting force of the other fan to control tilt of the plane.

7. Apparatus as in claim y6 and means permitting the automatic actuator to be overruled by the roll trim stick apparatus.

References Cited UNITED STATES PATENTS 3,033,492 5/ 19612 Rowe n 244-23 3,146,590 9/1964 Erwin 244--23 X 3,154,917 ll/l964 Williamson 244-23 X 3,412,959 11/1968 Wachter -y 244-52 FOREIGN PATENTS 982,765 2/ 1965 Great Britain.

JAMES E. PITTENGER, Assistant Examiner MILTON BUCHLER, Primary Examiner 

